MailDroid

MailDroid is an ad-supported WebDAV/POP3/IMAP Idle
Push mail client written from the ground up and and not based on the
stock Android mail
client.

Web-based Distributed Authoring and Versioning (WebDAV) is a
set of methods based on the HTTP protocol that facilitates
collaboration between users in editing and managing documents and files
stored on web servers.

MailDroid is an easy to use mail client for
the Android platform. It also has a good range of features. We
found the ads displayed on the free version to be a little too
distracting, and the Pro version (which removes
the ads) is a ridiculous $17.99.